Rhododendrons at Goldsworth
By Walter Slocock
Although there is an almost complete collection of the species that are hardy enough to grow here, there are unfortunately few that can be relied upon to make a display each year. It is to the hybrids that this duty falls and it is to their production that much of the work of this nursery is directed. Some of the best garden hybrids are very old indeed, but year by year new ones arrive to join them though seldom take their place. The purposeful crossing of rhododendrons have been going on for some forty years, though they have been grown here for at least a hundred or more. It has been mainly directed to the breeding of garden hybrids in the newer shades of cream, yellow, apricot and orange that the majority of crosses have been made and flowered.
Fig 15: R. 'Goldfort', one of the Goldsworth Nursery Plants
growing in the trial gardens at Wisley
Some success has been achieved as the popularity of 'Goldsworth Yellow', 'Butterfly', 'Dairymaid', 'Souvenir of W. C. Slocock' and 'W. C. Slocock', testify and lately 'China', 'Letty Edwards', 'Goldfort' (Fig. 15). 'Goldsworth Orange' and 'Tortoiseshell' to mention only a few have received the highest awards and have come to stay. I well remember as a boy the thrill my father had when 'Goldsworth Yellow' first flowered.
The breeding of these plants is interesting and perhaps instructive. Some plants stand out as being good parents while others though good in themselves are failures. It is necessary to have one good parent at least if progress is to be made. Campylocarpum and fortunei are good illustrations of this point. Both are outstanding parents of new rhododendrons, so that by selecting outstanding forms of each species and crossing together one would expect a fair result. R. 'Gladys' was the name given to one fine batch of seedlings, whilst our cross was named 'Letty Edwards' about the same time. Some forms have a red throat to the cream flower, some are tinged with peach and one which we think the best is a clear yellow devoid of any other marking. The best forms have had awards and are grown under numbers, the clear yellow variety being No. 31.
'China' is a cross between wightii and fortunei. Wightii has hitherto not shown any talent as a parent and in fact the series Lacteum do not impart vigor in their children. 'China' however is a break, it has combined the size and quality of the flower of fortunei - the seed parent - with the number of flowers and the cream coloring of R. wightii, the broad foliage of which it resembles. Lost, fortunately are the loose drooping truss of R. wightii and its straggling growth. These two examples only illustrate the result of crossing two species; what about the mongrels?
In attempting to obtain a race of hardy yellows, campylocarpum was used with many of the old Waterer hybrids, sometimes with extraordinary results. R. 'Butterfly' for example is R. campylocarpum x 'Mrs. Milner', an old fashioned wine red which used to be exported to the Eastern States. Of the traces of 'R. Mrs. Milner' only the truss and the vigor remain, the pale yellow colour and the leaf is entirely R. campylocarpum.
Many well known plants are very crossbred on at least one side of their parentage R. 'Goldsworth Pink', R. 'Goldsworth Crimson'; R. 'Red Riding Hood' and R. 'Lavender Girl' are just a few of such that we have selected from thousands of seedlings.
R. 'Goldsworth Orange' a first cross of R. dichroanthum x discolor, is a late flowering plant of moderate growth and though Winter hardy, its lateness caused it to be cut by an early October frost this year. The next generation of this plant are giving some fine results; x R. griersonianum - R. 'Tortoiseshell' is outstanding with such varieties as R. 'Wonder' (orange salmon) and R. 'Champagne' (amber), though as yet there is insufficient stock for disposal.
R. 'Royal Mail' - 'Romany Chai' x 'Tally Ho', is the most brilliant scarlet we have yet seen and takes its stamina from its grandparent 'Moser's Maroon', a very noted hybrid much used by the late Mr. Lionel Rothschild.
Work is now going ahead to breed a new race of larger flowered plants of all colors and short compact growth suitable for front row specimens and the smaller garden. Already there is 'Apple Blossom' to accompany such plants as 'Cilpinense' and 'Humming Bird' and we wait hopefully and patiently further generations of Post War hybrids with the blood of dichroanthum, repens, and williamsianum to fill this much needed gap.
During all this time many azalea seedlings were flowered, particularly of the deciduous type. One of the first to be selected for naming was 'Mrs. Oliver Slocock; (A. M. 1933), one of the few azaleas that cannot be termed a complete mongrel. A typical mollis x sinensis was crossed with 'Altaclarense' (Pontica x occidentale). It is remarkable that it comes almost true from seed though the size of flower varies. At its prime this plant has flowers ¾ inches across, of tangerine suffused with terra cotta, the outside of the bud and flowers being brick red. There are up to 18 pips in each truss.
The Knaphill strain which we have especially developed originated at Anthony Waterer's Knap Hill Nursery a few miles from here. Mr. Lionel Rothschild made great advances in the quality of this fine strain at the same time as we were working, and we were fortunate in being able to use pollen from each other's plants. All the blood that went into making this strain is not known, certainly pontica, occidentale, vaseyi, viscosa, calendulaceum to mention only some. As can be easily seen such plants are very mixed in origin but nevertheless they have certain characteristics on which we insist. They must have the wide, flat flower with a long slender trumpet shaped neck which gives lasting quality. Also they must be late enough to miss the early May frosts. Size varies from 2 inches across to 4 inches in some of the latest ones whilst colour varies from white to scarlet with the unusual pinks frequently associated with rhododendrons.
Our first series of named varieties are well established and contain such names as, 'Satan' and 'Tunis' - red, 'Seville', 'Fireglow' and 'Gog' in pale yellow and 'Persil - white. The next ones are on the way with larger flowers and new shades hardly dreamt of among deciduous azaleas.
Many Knap Hill azaleas have already found their way around the world and it is hoped that more will continue to do so, although the regulations at present in force seem designed that they should not, or at least that their chances of survival be impaired by the removal of earth.